76 



MACTRAD^. 



hinge margin being slightly concave, it is there somewhat nar- 

 rowed ; posterior slope convex, extremity slightly gaping, base reg- 

 ularly curved ; beaks but little elevated ; before, there is a short, 

 faintly defined areola ; behind them is another portion bounded by 

 an elevated line extending from the beaks to near the lower an- 

 gle, and here the epidermis is very coarsely and loosely wrinkled ; 

 the surface has a rugged appearance from the coarse lines of 

 growth, and is rendered still more rugged by the folds of the 

 thick, strong, dusky-brown epidermis in the same direction. In- 



Fig. 388. 



M. ovalis. 



terior bluish-white ; hinge-supports strong and smoothly rounded ; V 

 tooth strong and firm, having the anterior side in the right valve 

 much more elevated than the posterior ; lateral teeth short and 

 slender, not striated ; muscular and pallial impressions rather su- 

 perficial ; sinus of the latter deep. Length, three and one half 

 inches ; height, two and one fourth inches ; breadth, one and one 

 fourth inches. 



Found at the Bank fisheries, in the stomachs of fish. Eastport 

 and Grand Manan, at low-water mark, large and plentifvd ; and 

 southward to Cape Cod (Stimpson) ; Sable Islaiul (Wil/is) ; Gulf of 

 St. Lawrence (^Bell). The young, from a fourth of an inch to an 

 inch in length, are found abundantly in fish caught in Boston Har- 

 bor. At least, they differ from the young of M. solidissima, and 

 correspond in external proportions and appearance to our shell, 

 and the teeth are slender and without striae. Middcndorff gives 

 the Sea of Ochotsk, and Wossnessenski gives Behring's Straits as 



